Lima beans have a plant structure similar to other bean plants. Yet, while they share common features, they still manage to produce a fruit that is different from all other beans. Understanding the components of the plant and how they relate to one another leads to a deeper appreciation for the plant and how it develops its beans, especially if you want to grow some.
Roots serve two important purposes for the lima bean plant. First, they anchor the plant in place. The second function is to absorb water and nutrients from the soil and distribute it to the plant. Bean plants in general have shallow root systems, so they tend to spread out horizontally more than vertically. Tiny root hairs branch off the main root, reaching out and seeking what the plant needs to survive.
Lima beans come in both pole bean and bush bean varieties. In both cases the stems are crucial. Stems also have two primary functions. The first function is to act as the skeleton of the plant and provide support. The second is to house the vascular bundle. Inside the stem are tubes which comprise the vascular bundle. The xylems are the tubes that carry water from the roots to the rest of the plant. The phloems are the tubes that carry the sugary food the leaves make to the rest of the plant.
Leaves are critical to a plant's survival because they make the plant's food through photosynthesis. Leaves are attached to the stem by the petiole. The petiole extends up through the leaf and is called the midrib. The underside of the leaf is where the stomata are--the tiny openings that open in sunlight to take in carbon dioxide.
Lima bean plants have tiny white flowers. These develop when the plant is mature enough to begin its reproductive cycle. Flowers of determinate varieties last about two weeks while indeterminate varieties will bloom throughout the growing season. Flowers must be pollinated by an outside pollinator such as a bee or butterfly.
Once the flowers have dropped off, the bean pods begin to develop. From start to finish, the lima bean takes anywhere from 60 to 110 days to reach maturity, depending on the variety. Some are picked early before the pods begin to swell. These are used as baby lima beans. Mature beans are picked when the pod swells but is still a bright green. If the pods are left to dry out naturally, the beans will become seeds and begin the growing process over again.